Is this maybe what happens when Themeswitcher crashes: While the desktop background still gets changed, the Colorscheme does not get set to Basic? How to avoid the crashing FileIOException? What fileIO may a colorscheme change require?

Disruption is the least of the problem: The warning comes up when computers become dangerously slow. In the past, they have become disfunctional during these episodues and needed to be power-cycled. This has resulted in loss of assignment and assessment materials.

For language lab use, stereo is more important than usual, since the channels may carry source versus translation/interpretation, L1 versus L2, teacher versus student, model versus imitation and so forth.

You can choose which channel to listen to by adjusting the balance for stereo playback.